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About the Beauly-Denny project

The full length of the Beauly-Denny line has been successfully energised and is now operating at up to 400 kilovolts.

The 220km replacement overhead line was developed jointly by Scottish Hydro Electric Transmission plc and SP Energy Networks, which own and invest in the high voltage electricity networks in the north and south of Scotland respectively.

The new line is supported by 615 steel towers, replacing over 800 pre-existing 132 kilovolt towers that were built in the early 1950s. The renewal of the north-south spine of Scotland’s electricity network has supported more than 2000 jobs over a 7 year period. It is the longest transmission line to be built anywhere in the UK in recent times and crosses the highest and most inaccessible terrain on the Great Britain transmission system at the 2526ft summit of the Corrieyairack Pass.

Find out more

We have created five short films which explain what is involved in a project that benefits an entire country. Whilst the Beauly-Denny project was impressive in its size and complexity, the methods of development and execution detailed in the films apply to all major overhead line projects undertaken by Scottish and Southern Electricity Networks.

Preparing for a major overhead line project

Preparing for a major overhead line project

This film describes the steps required to be undertaken before an overhead line can proceed into construction. Development teams will regularly develop a project over months and years before submitting a planning application. Following a successful planning application being received, a significant amount of preparation work is required to be completed in advance of the construction phases.

Beauly-Denny Groundworks

Groundworks

This film helps explain the enormous efforts required to be undertaken before any new electricity structures can be erected. Teams of tree cutters and civil engineers will lead the way to ensure safe access can be made to multiple construction sites. During these initial stages, the teams focus on how to minimise potential impacts on communities and the environment. Completion of safe access then allows skilled engineers access to begin construction of the tower foundations, some would argue these are the most important part of an overhead line.

Tower Construction

Tower Construction

This film provides an insight into what is involved in erecting steel towers that are capable of transporting 400,000 volts. The constructions team faced severe weather whilst working in some of Scotland's most challenging environments. The Beauly-Denny project has claim to the highest located transmission tower in the UK, located over 2,500ft up a mountain. Engineers had to coordinate works with weather windows and also with members of the public which has led to the use of ingenious construction methods.

Rationalisation and Dismantling

Rationalisation and Dismantling

The Beauly-Denny project had unique conditions associated to its Section 37 consent that required the undergrounding or complete removal of lower voltage overhead. These conditions were imposed upon the project to help reduce the overall visual impact of overhead lines in specific areas including the Cairngorms National Park. The final stages of the Beauly-Denny project required the dismantling of over 600 old towers and reinstatement of access tracks created at the beginning of the project, a significant undertaking which required care and attention.

Substation Development

Substation Development

This film highlights the importance of substations within the electrical network. Without substations, energy could not be transported safely around the country to those who require it. They require a large amount of civil works ahead of the construction and delivery of equipment that can weigh up to 180 tonnes.

Legend

The data in this map is provided for indicative purposes only and may be subject to change. Scottish Hydro Electric Transmission plc do not accept responsibility for its accuracy, completeness or validity. The data should not be copied, reproduced or utilised externally without permission.

Investments in projects are made by SHE Transmission plc. Electricity transmission companies are authorised to recover the costs of such investments through 'use of system' charges which are levied by National Grid Electricity Transmission plc on generators and suppliers of electricity. Suppliers recover their costs from all electricity customers. In order to protect the interests of customers, the transmission companies have to demonstrate to the energy regulator, Ofgem (Office for Gas and Electricity Markets) that proposed investments are necessary, are efficient and are economical so that the charges which are ultimately levied on all electricity customers are justified. This means SHE Transmission is subject to a funding mechanism established by Parliament and regulated by Ofgem. Cross subsidies between different businesses in the SSE group is not permitted.

The Scottish Ministers are responsible for determination of applications submitted under Section 37 of the Electricity Act 1989. Both statutory consultees and members of the public have the right to submit their representations on the application. All representations will be considered by Scottish Ministers in their determination of the application.The Office for Gas and Electricity Markets (Ofgem), as the regulator, has to approve all investment so project proposals are developed under license conditions. Preferred route corridors chosen will comply with revised ‘Holford Rules’ which are the recognised industry approach to routeing overhead lines amended to reflect Scottish circumstances.

The Holford Rules originated in 1959 as the result of work by Lord Holford, a part-time member of the Central Electricity Generating Board (National Grid's predecessor). The Holford Rules have been augmented by both National Grid and SHE Transmission plc to reflect environmental legislation and best practice in recent years. We have continued to use them as a valuable set of guidelines for reducing the impact of our assets on landscapes. The guidance recommends appropriate application of the Holford Rules to inform routeing. These rules advocate the application of a hierarchical approach to routeing which first avoids major areas of highest amenity, then smaller areas of high amenity, and finally considers factors such as backdrop, woodland and orientation. The Holford Rules apply the term ‘amenity’ to refer to environmental designations and classifications such as Natura 2000 sites, Sites of Special Scientific Interest (SSSI), Scheduled Monuments, Listed Buildings, National Parks.The guidance also recognises that the key effect of overhead lines is visual and it advises that the routeing of overhead lines should consider the types of mitigation (screening) that could offset any visual effects. In their National Policy Statement EN-5, the Government has stated that the Holford Rules “should be followed by developers when designing their proposals.” Their use is therefore Government policy, rather than a voluntary choice of SHE Transmission plc.

SHE Transmission are regulated by the Office for Gas and Electricity Markets (Ofgem), the regulator responsible for representing consumers' interests. Electricity consumer interests are therefore one of our key drivers and this is enshrined in our statutory duties under the Electricity Act. In particular we have a statutory duty to develop, maintain and operate an efficient, economic and co-ordinated transmission system. Since the costs of these projects will ultimately be paid for by electricity consumers, we have a responsibility to take cost into account with due weighting in a comparison against other important factors.

It’s the highest voltage electricity network in the UK – the ‘motorway network’ of the energy world. It transmits large quantities of electricity over long distances via wires carried on a system of mainly metal towers (pylons) and large substations. Transmission voltages in Scotland are 132kV, 275kV and 400kV. Larger generation schemes usually connect to the Transmission system.

The lower voltage parts of the system are called distribution networks. In Scotland, these local networks operate below 132kV whereas in England the distribution network includes 132kV.

New transformer energised at Fort Augustus Substation

14 Dec 2016 12:00

A 400kV Supergrid Transformer (SGT) and Reactor were successfully energised at SSEN’s Fort Augustus Substation this week enabling additional renewable generation to connect to the transmission network. SSEN Project Manager, Johannes Smit, said of the milestone: “The transformer was delivered in late October with final installation and commissioning taking place at the beginning of December. We have been in close contact with local residents to ensure that they are kept up to date during every stage of the process. To minimise any noise, we have increased the wall thickness of the transformer tanks for both the transformer and the reactor. Initial test results indicate that these measures have been effective.” Lead Project Manager, Archie Munro, said: “The Fort Augustus Substation was originally developed as part of the Beauly-Denny project. Since construction works commenced on the Beauly-Denny project there has been a significant increase in wind farm developments in the area. These additional reinforcements reflect our ongoing commitment to constantly upgrade and strengthen our network based on the needs of generators and our customers.”

Local Businesses

Scottish Power Energy Networks (SPEN) is the distribution network operator for central and southern Scotland, Merseyside and North Wales. It is also the Transmission Owner for the south of Scotland.

Address: www.spenergynetworks.co.uk

Balfour Beatty

Balfour Beatty’s power transmission and distribution teams work with regional, national and international electricity network owners and operators to provide technical engineering solutions.

Address: www.balfourbeatty.com

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